1. Field of the Invention
The invention relates in general to an image processing technique, and more particularly to a technique for managing/utilizing a memory in an image processing system.
2. Description of the Related Art
Accompanied with the ubiquity of various electronic products, multimedia systems such as home theaters are now prevalent in households. In many multimedia systems, one of the most important hardware devices is an image display apparatus. To satisfy viewer demand for realistic images, one dominant development trend is the continuously increasing size and resolution of an image. In general, large-size and high-resolution image display equipment needs to be equipped with higher operational speed and greater memory capacity.
FIG. 1A shows an exemplary block diagram of an image display equipment. A scaler 12 scales a size of an input image to match a size/ratio of the scaled image with the standards of a playback module 15, and performs image processing processes such as brightness adjustment, contrast adjustment and sharpening. As shown in FIG. 1A, the input image is first stored in a first dynamic random access memory (DRAM) 11. The scaler 12 is generally designed to process image data of the input image in a unit of a row. Thus, the scaler 12 includes a line buffer 12A for temporarily storing row data fetched from the first DRAM 11. For example, if a resolution of the input image is 1920(row)*1080(column) pixels, the width of the line buffer 12A needs to at least accommodate image data of 1920 pixels.
The scaler 12 sequentially generates the row image data of the scaled image, and stores the generated data into a second DRAM 13. After the scaled image is completely stored into the second DRAM 13, a frame rate conversion (FRC) module 14 accesses the scaled image from the second DRAM 13 and provides the scaled image to the playback module 15. If the frequency of inputting the input image is different from the display frequency of the playback module 15, the FRC module 14 deletes the redundant image or generates and inserts the deficit image, such that the image frequency outputted to the playback module 14 matches the setting of the playback module 15.
Conventionally, if the resolution of the input image is increased from 1920*1080 pixels to 3840*2160 pixels, the width of the line buffer 12 needs to be correspondingly augmented to accommodate image data of 3840 pixels from 1920 pixels. If the image processing process performed by the scaler 12 takes neighboring pixels of the vertical direction into consideration, the line buffer 12A is mandated to temporarily store image data of several rows of pixels at the same time. For example, to process the third-row data in FIG. 1B, image data of the first-row to the fifth-row pixels (with data of the first, second, fourth and fifth rows serving for auxiliary purposes) are temporarily stored in the line buffer 12A at the same time. Thus, it is seen that the absolute value of the capacity of the line buffer 12A must be significantly increased given that the resolution of the input image is increased.